Question: On page two of the Assembly and Operators Manual that came with my Mig21 (version 20050329 per back cover) there is mention of four lock nuts in addition to four butterfly nuts. I cannot find these four lock nuts. What should I do?

Answer: The lock nuts were difficult to install and remove when used in conjunction with butterfly nuts. We are now using a better grade of butterfly nuts that do not require the use of additional lock nuts. Lock nuts are no longer included with the Mig21. If you do not wish to remove the wings for transport and want a longer term solution to ensure the butterfly nuts remain snug, use medium thread locker such as Z42 from Pacer.

In any event, check the butterfly nuts before each flying outing to ensure they are snug (do not overtighten or you will strip the studs) and retain the wing securely attached to the fuselage.